Brakes

[grashley]

I finally got my last new tire installed today (waiting for shipment) and had the brakes looked at at Best One Tires.  Initially, at gain 4, the FW brakes could not hold the truck in place when in gear at idle.  At gain 10 (max), it held.  His inspection found the front axle tires could not be turned by hand with brakes applied, while both rear axle wheels were free spinning.  Found and repaired broken wires, which fixed the issue.  No tires could be turned by hand with brakes applied.  Now, going 5 mph at gain 4, trailer brakes slowly slow the rig down.  At gain 10, it will stop the rig in 10 - 15 ft.  (Trailer brakes only).  Mechanic says GREAT!  They're fixed!  I'm not convinced.

This is my first big camper.  My expectation was that at gain 10, the trailer brakes should be locking up at 5 mph on gravel, not just slowing me down.  I expected to lock the brakes on gravel at gain 5 or in that neighborhood.  Then back off 0.5 - 1.0 for normal operation.

Help me understand.

 

[lynnmor]

Help me understand.

Read your owners manual, your factory trailer brake system is designed to provide little braking below 11 MPH, to prevent jerking.

 

[SargeW]

Did the mechanic pull the drums and check the brakes and grease seals, or just inspect from the rear? The star wheel adjusters may need adjusting to set the brakes distance from the drum.  Some drum brakes are self adjusting, some are not.

 

[Gary RV_Wizard]

That sounds like fairly normal for electric trailer brakes, though a little on the light side.  You really don't want them to lock up easily, so brake adjustment usually errs on the side of light rather than heavy braking.  I would expect to run the controller at a setting in the 5-7 range to get good braking and reserve the under 5 or near-10 settings for special circumstances.

Wiring is often a problem in electric brake systems, both tow vehicle and trailer wires. Inadequate size (wire gauge) and poor connections are rampant, causing voltage and amp  losses throughout.    Further, the brakes on the trailer axles are near always undersized, since the axles only carry about 80% of the weight of a 5W.  The brakes are sized to the axle capacity, not the total 5W weight, so even perfectly good brakes are NOT going to stop the trailer all that quickly. Add another 6000-8000 lbs of truck and it's lucky if they stop the whole rig at all.

 

[grashley]

Did the mechanic pull the drums and check the brakes and grease seals, or just inspect from the rear? The star wheel adjusters may need adjusting to set the brakes distance from the drum.  Some drum brakes are self adjusting, some are not.

He did NOT pull drums, just inspected from the rear.  Since the wheels did not turn when in the air and brakes applied, no adjustments were made.

 

[SargeW]

Hmm, it easy to stop a wheel suspended in the air, not so much with 10,000 pounds pushing it down the road. Usually to adjust a drum brake you turn the star adjuster until the shoes start to drag, then back it off a half a turn.

 

[Gary RV_Wizard]

This etrailer article on trailer brake adjustment may be helpful:
https://www.etrailer.com/question-88379.html

 

[SargeW]

Good article Gary, thanks.